CHY 116 Friday 1:15-4:00
Lab Conducted on 4-12-13 and 4-19-13 4-26-13
This lab was conducted in order to determine the chemical composition of an unknown organic acid. A known mass of acid was dissolved into 30mL of either water or methanol (depending on solubility) and titrated with standardized sodium hydroxide. Data from this allowed the molar mass of the acid to be calculated if it was either monoprotic or diprotic.
|Trail |Acid Used (mg) |Concentration of base |Volume of base (mL) | |1 |265 |0.0981 |27.9 | |2 |268 |0.0981 |34.7 | |3 |262 |0.0981 |29.4 |
Calculations were completed as follows:
Vol. of NaOH added (mL) * 1L/1000mL * 0.981mol NaOH/L = moles of NaOH added For monoprotic acid (R-COOH): Moles of Acid = Moles of NaOH
Mass of acid (g)/moles of Acid = Acid’s molar mass (g/mol) For Diprotic acid (R(COOH)2): Moles of acid = ½ * Moles of NaOH Mass of acid/moles of acid = Acid’s molar mass (g/mol)
To further enforce the conclusions drawn regarding the acids identity from the titration (crotonic acid for my sample), NMR spectra were given for the unknown acid. A little bit of research reveals that the NMR spectra for crotonic acid is exactly what was given on the Human Metabolome Database (http://www.hmdb.ca/). Copies of their NMR spectra are printed and though this data is pretty convincing, it can only be reinforced. Three more tests were conducted.